There may not be a direct relationship between the completion of the third dose of the New Crown vaccine and delayed menstruation, which is considered to be related to physiological factors such as stress and sleep deprivation, as well as endometritis and polycystic ovary syndrome. 1. Physiological factors: Delayed menstruation can be caused by recent mental stress, lack of sleep, overwork, etc. Usually, no special treatment is needed, and it is not directly related to the completion of the third vaccination of XKV vaccine. 2. Endometritis: the disease is related to pathogen infection, while sexual life, gynecological surgical operations, etc. are triggering factors. Common symptoms include lower abdominal pain, fever, prolonged menstrual period, etc., which may be manifested as delayed menstruation and is not directly related to the completion of the third injection of the new crown vaccine. 3. Polycystic ovary syndrome: the cause of the disease is not clear, but it may be related to genetic and environmental factors. The disease may cause delayed menstruation in some women, and may be accompanied by symptoms such as hirsutism, infertility, and scanty menstruation, and is not directly related to the third dose of the New Crown Vaccine. There are many clinical reasons for delayed menstruation, such as taking birth control pills, endometriosis, etc., which are not directly related to the completion of the third dose of the new crown vaccine. It is recommended that those who have delayed menstruation after the third dose of the vaccine should consult a doctor for an examination to determine the cause of the disease and follow the doctor’s instructions.